Field of the Invention
This invention relates to systems and methods for reducing stress on RAIDS undergoing a rebuild process.
Background of the Invention
A RAID (i.e., a Redundant Array of Independent Disks) is a storage technology that provides increased storage functions and reliability through redundancy. A RAID is created by combining multiple disk-drive components (or other storage components such as solid state drives) into a logical unit. Data is then distributed across the drives using various techniques, referred to as “RAID levels.” The standard RAID levels, which currently include RAID levels 1 through 6, are a basic set of RAID configurations that employ striping, mirroring, and/or parity to provide data redundancy. Each of the configurations provides a balance between two key goals: (1) increasing data reliability and (2) increasing I/O performance.
When a disk-drive component of a RAID fails, the RAID may be rebuilt to restore data redundancy. This may be accomplished by replacing the failed disk-drive component with a standby disk-drive component and copying and/or regenerating the lost data on the standby disk-drive component. Ideally, the RAID will be rebuilt as expeditiously as possible to minimize the possibility that another disk-drive component will fail and result in permanent data loss.
Unfortunately, when a RAID is being rebuilt due to a disk failure, additional stress is typically placed on the RAID that may cause other disk drives in the RAID to fail. This may be at least partially due to the fact that I/O may still be occurring on the RAID while it is being rebuilt. This may also be due to the fact that disk drives in a RAID may be of similar age, brand, size, etc., and when one disk drive fails, other disk drives may be on the verge of failing. The additional stress placed on the RAID during the rebuild process may be enough to induce these already-weakened drives to fail. Unfortunately, if another disk drive fails before the RAID has had a chance to rebuild, permanent data loss may occur.
In view of the foregoing, what are needed are systems and methods to reduce stress on RAIDs undergoing a rebuild process. Ideally, such systems and methods will avoid permanent data loss as well as improve I/O performance.